The invention pertains to an access system of the type indicated in the introductory clause of claim 1. The door handle is first moved by a motorized actuator between a first or retracted position, in which it cannot be gripped effectively, to a second or extended position, in which the human hand is able to grip the handle properly. In the retracted position, the door lock is closed, which is also true for the second, extended position. Starting from that position, however, the handle can be moved further by hand into a final position, in which the door lock can be opened by mechanical control means.
In the known access system of this type (DE 197 40 827 A1), the actuator consists of a drive element, which can be moved between three different pivot positions by actuation of a lock cylinder or by a motor; a drawbolt projects from one side of this actuate, a pushbolt from the other. The handle comprises a cover, which, in the first or retracted position of the handle, is flush with the exterior skin of the door to prevent the intrusion of dust and moisture into the handle recess. In this first, retracted, position, the drawbolt grips under the linkage of the door handle and prevents the door from being opened in an emergency, e.g., when the electronic circuitry fails. In the retracted position, furthermore, the cover, which is flush with the door, cannot be gripped effectively to make it possible for the door to be opened in an emergency.
In another known access system of this type (U.S. Pat. No. 5,873,274), the door handle is spring-loaded to move outward. In its retracted position, a locking bolt engages positively in openings in the handle and holds it in the retracted position. When a key is used to actuate the lock cylinder, the bolt releases the handle, as a result of which the spring can move the handle into its extended position. The return of the handle from the spring-loaded extended position to the retracted position must be accomplished manually. Because of this manual return, the handle cannot be operated remotely.
In an access system of a different type (DE 198 16 603 C1), it is known that the handle can be gripped by hand while it is in its first handle position and moved manually to a second handle position, where normally a blocking element prevents further movement to the third handle position. The blocking element is removed only after the identification means in the vehicle accepts the access authorization; as a result, the handle can then be moved into its third position. In this known access system, it is necessary for it to be possible for the human hand to grip the handle reliably in its first handle position. For this purpose, there must be sufficient room to bring the hand to the handle and/or to the adjacent exterior door panel. This design causes an undesirable increase in the amount of drag on the vehicle when it is in motion. In addition, the state of the art just described involves a keyless access system, in which the failure of the electronic circuitry cannot be tolerated. This latter aspect limits the range of applications of this known access system. Because the handle is spring-loaded and thus is always trying to return to the first handle position, it would be possible in the known access system for the hand to be caught if the person were to hold onto the handle too long. But if the handle is released before that, e.g., while it is in the outermost, third handle position, very unpleasant noise is produced as the handle moves back under the force of the spring into its first handle position.
The invention is therefore based on the task of developing an access system which is streamlined when in the retracted position, which can also be used in the case of door lock controlled by a lock motor, and which can be operated reliably even in an emergency, when the electronic circuitry fails. This is accomplished according to the invention by the measures to which the following special meaning attaches:
A cam is used as the actuator, on which the door handle or its linkage is supported; in the rest position, the linkage is supported nonpositively on the point of minimum eccentricity of the cam, and when in the working position it is supported on the point of maximum eccentricity. The profile of the cam forms an adjustable stop for the door handle or its linkage. For this reason, the invention can also be used in an access system in which the door lock is controlled by a lock motor. That is, starting from the second or extended position, the door handle or its linkage can be lifted away from the maximum eccentricity of the cam and moved into a fourth or pulled-out position, which is between the second or extended position and the third or final position. In the pulled-out position, the lock motor is rendered operative.
The invention can also be applied just as effectively in an emergency, when the electronic circuitry fails, as it can in an access system without a lock motor. In this case, the previously mentioned fourth or pulled-out position is simply omitted, and the door handle or its linkage can be lifted manually away from the point of minimum or maximum eccentricity and moved to the third or final position, in which the door lock is opened via mechanical control means.
In an access system which controls the door lock by way of a lock motor, there no danger that the hand will be caught when the handle is moved back from its fourth or pulled-out position to its second or extended position. That is, the further return of the handle to its first or retracted position occurs electrically, where the cam is turned back with respect to the handle or its linkage from its point of maximum eccentricity to its point of minimum eccentricity. Even though force may be exerted on it, the door handle returns to its retracted position with practically no noise at all.